Is the worshiper required to be fearful of God or tranquil in Him during prayer, and is tranquility and comfort in prayer considered a trivialization of it?

A Muslim should combine fear and hope in their prayer. They should approach their Lord with their heart, gathering hope for His grace and fear of Him, and contemplating the verses and remembrances they recite. If they recite something that inspires hope, they should feel hopeful and think well of their Lord. If they recite something that inspires fear, they should feel apprehensive and think poorly of themselves. The heart's joy and smile when praising Allah are good and permissible. They must adopt the means of achieving khushu' (devotional humility) and strive to attain it, performing their prayer with attentiveness, presence of heart, tranquility, and serenity.